Electrohygrostat



May 16, 1933. M. o. SNEDIKER ELECTROHYGROSTAT Filed June 10, 1931 2Sheets-Sheet l y 1933 M. o. SNEDIKER 1,908,927

ELECTROHYGROSTAT Filed June 10, 1951 2 Sheets-Sheet 2 Patented May 16,1933 UNITED STATES PATENT? OFFICE MORTON O. SNEDIKER, OF CHICAGO,ILLINOIS, ASSIG-NOR TO THE POWERS REGULATOR COMPANY, OF CHICAGO,ILLINOIS, A CORPORATION OF ILLINOIS ELECTROHYGROSTAT Application filedJune 10, 1931. Serial No. 543,379.

My invention relates to devices for controlling the moisture content ofair and particularly to a device of this character in which electricalpower is used for actuating the moisture admission apparatus.

I am aware that electro-hygrostats have been suggested and severalthereof operate satisfactorily where low voltage current is utilized orwhere a low voltage relay circuit is employed. The latter design isobjectionable because of the additional cost of apparatus, .includingtransformers, etc.

An object of my invention is to provide an electro-hygrostat in whichhigh voltage current is exclusively used. In order to avoid destructivearcing at the contacts special novel apparatus is utilized, andcontinued satisfactory operation over long periods is assured. Toaccomplish the desired result I utilize the principle of supplementingthe contact effectedv by the moisture-sensitive element by motiontransmitted to the contacts by the action of the magnet utilized toclose the primary circuit. This in itself is not new, but variations andimprovements 7 are made which render such devices less troublesome. Forexample, a common fault is that arising from an abnormally closedcircuit due to adherence of the secondary contacts by fusing. In myapparatus the arrangement is such that the powerful expansive force ofthe moisture-sensitive element-is available to separate the contacts incase of incipient fusion. This implies relatively great rigidity of thefixed contact piece and consequently the requirement for relativelygreat force in order to flex said contact piece to assist in the makingof the original contact. This is secured by proper arrangement of theparts that will now be described.

My invention will be more readily understood by reference to theaccompanying drawings in which:

Fig. 1 is a side elevation of an electrohygrostat' constructed inaccordance with my invention;

Fig. 2 is a similar view showing the parts in another position, and

Fig. 3 is a plan view.

In the drawings the device of my invention is shown as mounted on ahollow base 10 and includes a moisture-sensitive element 11 abutting atone end against an adjusting screw 12 and at the other end against theshort arm 13 of a bell crank fulcrumed at 14. The other arm 15 of thebell crank carries a contact piece 16. The complementary contact piece17 is mounted on a relatively rigid arm 18 of insulating material fixedto a support 19. An insulating material, such as fibre, isselected'having considerable rigidity but still sufiiciently flexibletoenable its being bent the small amount necessary. Wires extending fromthe contacts 16, 17 constituting the secondary circuit, extend to amagnet 20, the projecting core of which.

serves to actuate an armature 21. The armature is mounted foroscillation on a fulcrum piece 22, the projecting outer end 23 of thearmature being curved or angular as shown,

The armature also carries an arm 28 having a circuit closer 29 thereonfor closing the primary circuit indicated by the contacts 30, this armbeing resiliently connected through the spring 31.

In Fig. 2 the parts are shown in idle or inactive position in which casethe flat surfaces of the member 24 and the projection 23 are in contactand the armature is permitted to be drawn toward the core to an extentsufficient to close the primary circuit 30 with very little force.However, as the arm approaches the point of contact with the core, thefoot 27 has been elevated in contact with the contact piece 18 and muchgreater force is necessary and available in order to slightly bend saidcontact piece 18. At that point the parts 23 and 24- change theirposition, the part 24 rocking on the curved portion at the end of thestraight part of the armature projection thus exerting an augmentedforce or leverage and I exerting the full force of the magnet centage ofmoisture the expansion of the moisture-sensitive element results in athrust on the bell crank. This thrust being of relatively great force,and as the contact piece 18 is relatively rigid, any partial fusingofthe contacts 16, 17 will be broken and immediately upon breaking thecircuit through the magnet, the pressure will be released be neath thecontact piece and the circuit will be completely broken without an arc.

Thus I am able to utilize high voltage current without excessive arcingby reason of the proper arrangement of the parts. This result may beaccomplished in manners other than herein shown, and I do not wish to belimited except as indicated in the appended claims.

I claim:

1. In combination, a support, a moisture sensitive element thereon, anarm movable by said element, said arm carrying an electrical contact, arelatively rigid but slightly resilient arm fixed to the base andcarrying a complementary contact, a magnet and armature, a second pairof contacts adapted to be closed by said armature, said armature beingpivotally mounted, an arm connected at one end to the armature and atthe other end underlying said resilient arm, the connection between thearmature and arm being resilient.

2. In combination, a support, a moisturesensitive element thereon, anarm movable by sa1d element sa1d arm carrying an electrical contact, arelatively rigid but slightly resilient arm fixed to the base andcarrying a complementary contact, a magnet and armature, a second pairof contacts adapted to be closed by said armature, said armature cuit, apivoted armature, a second 'circuit' closer carried by the armature, acontactassisting arm resiliently connected to and adapted to be moved bythe armature and having a portion engaging the bendable contact arm, andmeans in said resilient connection for changing the leverage exerted bythe armature on said contact-assisting arm.

4. In a hygrostat, the combination of a moisture-sensitive element, abell crank, one

arm of which is contacted by said element,

and the other arm carries one of a pair of high voltage contacts in acircuit, a relatively rigid bendable arm carrying the second of the pairof contacts, a magnet in said circuit, a pivoted armature, a secondcircuit closer carried by the armature, a contact-assisting armresiliently connected to and adapted to be moved by the armature andhaving a. portion engaging the bendable contact arm, a means in saidresilient connection for progressively increasing the force exerted bythe armature on said contact assisting arm.

5. In a hygrostat, the combination of a moisture-sensitive element, abell crank, one arm of which is contacted by said element and the otherarm carries one of a pair of high voltage contacts in a circuit, arelatively rigid bendable arm carrying the second of the pairofcontacts, a magnet in said circuit, an armature in the general form of abell crank having the portion at one side of its fulcrum overlying thecore of the magnet and the portion on the other side of the fulcrumproviding an operating member, a contact-assisting arm for engaging saidcontacts, said arm having a fiat surface, spring held against a. fiatsurface on said member, whereby the energized position of the armatureresults in a spring resisted rocking movement in the connection between,the arm and the armature and a change in the leverage exerted by thearm.

In testimony whereof I have afiixed my signature.

MORTON Q. SNEDIKER.

